1. Field of the Invention
This invention relates to a liposuction apparatus and method. Particularly, this invention relates to a liposuction apparatus with the cannula shaft mounted via a swan neck to a handpiece and axial lumen passage, and is ideally suited for smooth continuous fat removal. More particularly relating to long, highly flexible metal or plastic cannula shafts which include a removable metal member.
2. Description of the Prior Art
Liposuction, which literally means xe2x80x9cfat suctionxe2x80x9d, is a technique that pulls fat out of the body by means of teasing, pulling, scarping, or suction. It can be used to reduce the volume of fat in many regions of the body, but is particularly effective in areas such as thighs and abdomen, which contain genetically determined fat not responsive to diet or exercise. Liposuction is currently an established modality in cosmetic surgery, performed by surgeons as an elective operation, and is one of the most common procedures in medicine.
All existing ultrasonic liposuction devices used in surgery, especially those with short rigid shafts, can cause complications and trauma by failing to have proper temperature control and improper placement in addition to increased entrance wounding.
A commonly accepted liposuction technique utilizes a cannula with a blunt closed bullet-shaped tip rather than an open tip or a pointed or sharpened tip. This cannula is a metal tube, about the size of a pencil, which is attached to a suction pump. The cannula, with its rounded tip, is sometimes passed though the fat first, without suction, to develop the proper passageway. Then suction is applied and the surgeon continues passing the cannula through the fat tunnels with repeated radial thrusts on several levels of the tissue. Adipose tissue is aspirated through a hole in the side of the cannula near its distal end. The cannula must be moved back and forth through each tunnel. Problems associated with this technique are similar to those experienced with the older methods of liposuction and include: oversuctioning, need for many entrance incisions, difficulty positioning patient, bleeding, and the resistance to passage in fibrous tissues.
Today there exists a wide variety of cannulas which allow surgeons to work more skillfully. For example, there is a bullet shaped tip, or curette-cannula where the suction holes have sharp edges. Rounded or bulbous shaped cannulas, such as bullet or basket-shaped tips, provide three dimensional forces on tissue at the tip which is concentric and conical. The disadvantage of these forces in penetrating highly fibrous fat tissue is that there is likelihood of increasing trauma to these areas vectoring particularly in highly fibrous fat tissue. This force vectoring has the consequence of increasing trauma to these areas. U.S. Pat. Nos. 4,886,491 and 5,514,086 to Parisi et al, both of which are incorporated by reference, describe cannula tips.
A spatula cannula provides a two-dimensional force which allows for greater ease of movement with less exertion on the surgeon""s part. The spatula concept has been incorporated into the design of the CAPISTRANO(trademark) line of cannulas. The CAPISTRANO(trademark) cannulas, marketed by Jeffrey Allan Klein, Md., Inc., San Juan Capistrano, Calif., are more rounded and the bevel is oriented more along the center-line and in longer cannulas. Any increase in roundness or bluntness causes increased resistance to passage and thus affords less predictability and bending of an extending probe with patients.
It is also known to use ultrasonically vibrating and aspirating probes in the field of liposuction surgery, as described in U.S. Pat. No. 4,886,491 to the present inventors. The procedure is to introduce the vibrating probe into the area of material desired to be removed which has been preirrigated, and use the ultrasonic vibrations to physically breakup the fatty tissue or loosen it from a fibrous encasement. The fatty tissue can be emulsified by ultrasound and aspirated through the probe, using irrigation as an adjunct. It is known that a particularly effective probe for ultrasonic liposuction is a hollow cylindrical probe with a bullet shaped tip on the distal end. The tip can be welded or otherwise affixed to the probe. Both probe and tip can be manufactured from a variety of acoustically conductive metals such as cold-rolled steel, titanium, and aluminum. In presently known devices, the probe and tip are manufactured from the same materials, or from very similar materials, to ensure effective propagation of the ultrasonic waves all the way to the tip of the probe. Propagation of the waves to the distal tip of the probe is desirable, because this causes the tip of the probe to be able to loosen and emulsify fat, facilitating insertion of the probe into the fatty tissue.
In previously known liposuction techniques, before the use of ultrasound, considerable physical exertion was necessary to force the tip of the probe into the fatty tissue. This was time consuming and required more openings, and it required considerable strength on the part of the physician. The currently known ultrasonic liposuction probes are much more easily moved through the fatty tissue, because the vibrating tip of the probe can loosen the tissue in advance of the probe""s shaft passage. This essentially breaks a hole through the fatty tissue, rather than punching a hole by stretching forces.
There is a disadvantage sometimes associated with an ultrasonic probe having an acoustically conductive tip, however. For instance, when the probe has been inserted into the fatty tissue near the skin or the peritoneum, resistance can be met. When resistance is met, the wattage or temperature at the tip increases, and it can increase to the point of damaging the skin or the peritoneum or nerves. During such manipulations, the heat generated at the tip of the probe may be in excess of the ability of the tissues to safely dissipate the heat. In other words, if care is not exercised, the tip may be hot enough to bum tissues, damage muscles, blood vessels, or nerves, and even penetrate membranes such as the skin or peritoneum.
Another problem regarding the liposuction procedure involves the reduction or elimination of friction caused by the motion of the cannula by the surgeon. Applying lubricating jellies and the use of plastic stents are not satisfactory since the jellies must be constantly re-supplied and the plastic stents are difficult to maintain in position. A further problem in liposuction is that most liposuction cannulas are comprised of rigid shafts that are manufactured to be straight without deviation. The human body however is comprised of an outer thin epidermis that overlies the dermis (leather layer of the skin that varies from xe2x85x9 inch to xc2xc inch in thickness in most body areas where liposuction is performed). The dermis overlies a layer of suction-able subcutaneous fat that is usually a strip varying from fractions of inches to several inches in thickness depending upon the patient. All three layers epidermis, dermis and fat have one thing in common, that they are curved. Again, unfortunately, liposuction cannulas are straight and rigid with a resulting forceful passage within the patient that does not conform to the curved contour of the target fatty layer or the layer of dermis that contains, envelops, binds or holds the fat in place. The passage of straight, rigid, unbendable cannulas often results in trauma called end hits and is frequently seen during surgery as temporary tents. The net or web of intersecting straight rigid liposuction cannula passages is thus not uniform in density through a curved target of fat.
There remains a need in the art for new devices and methods for removing fatty tissue without damaging skin, nerves, or organs or forming ridges and other disadvantages resulting from conventional or ultrasonic liposuction surgery. A need exists for devices and methods which would greatly assist those practicing liposuction to more efficiently removed unwanted fatty tissue, especially with reduced cannula entrance wounds.
Factors affecting a surgeon""s selection of liposuction shaft length and character may be numerous. These factors may include the following: ease of tip location detection with shorter cannulas, concerns of increased handle/shaft junction breakage with increased length secondary to length-induced leverage, the secondary need for increased shaft diameter to increase strength (durability) when a longer cannula is desired, the advantage of minimizing the number of holes by using longer cannula. The reinforced swan neck allows for an increase range of workable cannula length for a variety of flexible or inflexible metal shaft diameters. These attributes, together with the special tip bevel, allow controllable tissue penetration with novel motions that should reduce the number of entrance incisions, hasten the procedure, reduce the need for patient repositioning. These benefits have been attained without apparent increased bleeding or complications. The use of high memory, extended length cannulas allows for movements and attributes heretofore considered problematic. For example, unique approaches to xe2x80x9chard-to-researchxe2x80x9d areas, as well as decreasing the number of entry point openings, may modify a surgeon""s repertoire.
Along with the tip modification and swan neck modification changes, shaft specifications alterations have been made. The longer stainless steel shafts have been successfully used in all of our liposuctions performed numerous times. Stainless steel shafts in this cannula system are 2.0, 2.5, 3.0, and 3.5 mm in diameter. Currently available stainless steel tubing does not provide the flexibility or memory needed for proper function for shaft diameters exceeding 3.5 mm. However, certain alloys may enable an increase in diameter to about 5 mm.
Although shaft diameters between 2.0 and 3.5 mm provide surprising efficient and aggressive liposuction, many surgeons require cannula shaft diameters exceeding 4 mm to address obese patients and larger liposuction cases. However, metal cannulas with long shafts exceeding 3.5 mm in diameter of stainless steel were found on extensive testing to not possess the desirable qualities of a wide range of flexibility in combination with proper memory. The range for metal shafts is up to about 5.0 mm, preferably about 3.5 mm.
The present invention provides an improved system using plastic cannula shafts with removable internal memory metal support wires which satisfies the need for cannula shafts having diameters of 3.5 mm and up to 8 or 9 mm diameters. The first known use of memory wires in a plastic cannula is described and claimed in applicants U.S. Pat. No. 6,090,121 issued Jul. 18, 2000, entitled xe2x80x9cHighly Flexible, reinforced Swan Neck Liposuction Cannulasxe2x80x9d. This plastic/support wire system has been tested successfully. The invention, as in the above referenced patents allows controlled rigidity of the plastic shafts and the cannulas can be bent into a semi-circle without breaking and yet still return to the original shape due to the internal metal support wire which provides the memory for the plastic shafts. The metal support wire may either decrease in thickness toward the distal end or be mounted via a spheroid-shaped located at the distal end, and may be covered with a Teflon coating to prevent excess load heating during autoclave sterilization of the plastic shaft. The contact of metal and plastic in heat sterilization may cause melting or weakening of the plastic. Removability of the memory wire during autoclave sterilization eliminates any possible reaction between metal and plastic. Also, the reinforced swan neck may be provided with a disconnect which enables ready change of shafts of different diameters. Thus, the plastic cannula shaft system of the present invention, along with the above referenced metal cannula shaft system, provides a surgeon with the tools necessary to perform the complete spectrum of various liposuction procedures.
Straight and rigid liposuction cannula usage results forceful passage within the patient that does not conform to the curved contour of the target fatty layer or the layer of dermis that contains, envelops, binds or holds the fat in place. The net or web of intersecting straight rigid liposuction cannula passages is thus not uniform in density through a curved target of fat. The use of a highly flexible liposuction cannula shaft allows the shaft to curve within the target fatty tissues and within the curviform enveloping dermis. This allows for a more uniform suction effect within the fat and less probing and tangential scraping trauma to the dermis.
It is an object of the present invention to provide a long highly flexible cannula shaft having a diameter range of about 2 mm to about 9 mm.
A further object of the invention is to provide a liposuction device which includes a reinforced swan neck and a plastic cannula shaft.
Another object of the invention is to provide a liposuction system with a plastic cannula shaft having an internal metal support wire.
Another object of the invention is to provide a plastic cannula shaft with a reinforcing memory wire whereby the shaft can be bent into a semi-circle and returned to its original shape.
Another object of the invention is to provide a swan neck with a coupling arrangement whereby a variety of diameter cannula shafts can be easily connected using a glued seal or O-ring/threads.
Another object of the invention is to provide a plastic cannula shaft with an internal memory wire variable rigidity and thickness. Less flexibility is usually desired at the proximal end than at the distal end of the shaft. Alternatively, uniform flexibility may exist along the shaft length.
Another object of the invention is to provide a plastic cannula shaft with an internal memory wire which is attached at the distal end and is free floating within the plastic shaft.
Another object of the invention is to provide an internal memory wire of a plastic cannula shaft with a thermal protective coating.
Another object of the invention is to provide an internal memory wire comprising a removable spheroid-shaped member(or geometrically shaped distal mass) and wire.
Another object of the invetion is to provide a removable memory wire which can be removed from a plastic cannula during sterilization.
Another object of the invention is to provide a plastic cannula with a removable member (or geometrically shaped distal mass) and wire retained in the cannula tip by a spheroid-shaped member or block and spring arrangement.
Other objects and advantages of the present invention will become apparent from the following description and accompanying drawings. The invention involves highly flexible, reinforced swan neck liposuctions cannulas, and particularly long, flexible cannula shafts that can be bent and return to their original shape. The invention is particularly directed to plastic cannula shafts that exceed 2.5 mm in diameter and which include a removable memory wire. While metal cannula shafts have sufficient flexibility up to a diameter of about 3.5-5.0 mm, plastic cannula shafts have sufficient flexibility in the 2.5-9.0 mm range to enable being bent in a semi-circle and return to the original shape when the plastic shafts include an internal memory wire. The internal memory wire may be constructed so as to be thicker in diameter at the proximal end of the cannula shaft or mounted via a spheroid-shaped member and retainer means at the distal end. In addition, the memory wire may be coated with a heat resistive material while the plastic cannula shaft is steam autoclaved. Ultrasonic energy may energize a portion of the shaft other than the memory wire. Also, the memory wire may be removably attached at the distal end of the cannula shaft and be free floating adjacent the proximal end of the shaft. By providing a removable memory wire, problems associated with sterilization of a plastic/metal assembly are eliminated.